Composite produced by impregnating with cyclic carbonate oligomer and polymerizing

ABSTRACT

A composition comprising at least one oligomer of the formula ##STR1## wherein X is selected from the group consisting of alkylene of two to twelve carbon atoms, inclusive, alkylidene of one to twelve carbon atoms, inclusive, cycloalkylene of four to twelve carbon atoms, inclusive, cycloalkylidene of four to twelve carbon atoms, inclusive, ##STR2## a is zero or 1; n is an integer of one to about fifteen; 
     R is alkylene of two to eight carbon atoms, inclusive, or alkylidene of one to eight carbon atoms, inclusive; 
     R 1  and R 2  are the same or different and are alkyl or one to four carbon atoms, inclusive or halo; 
     b and c are the same or different and are an integer of zero to four; and 
     R 3  and R 4  are the same or different and are alkyl of one to eight carbon atoms, inclusive, or phenyl; and 
     d and e are individually integers of 0.1 or 2 with the proviso that d &amp; e is at least one.

This is a division of copening application Ser. No. 796,984, filed11/12/85, now U.S. Pat. No. 4,696,997.

BACKGROUND OF THE INVENTION

Polycarbonates are well known polymers which have good propertyprofiles, particularly with respect to impact resistance, electricalproperties, dimensional rigidity and the like. These polymers aregenerally linear, but can be made with branched sites to enhance theirproperties in specific ways. Low levels of branching are generallyincorporated into the resin by co-polymerizing into the polymer backbonea tri or higher functional reagent to yield a thermoplasticpolycarbonate resin with enhanced rheological properties and meltstrength which make it particularly suitable for such types of polymerprocessing procedures as the blow molding of large, hollow containersand the extrusion of complex profile forms.

Sufficiently higher levels of branching sites in the resin will causeresin chains to join to each other to form partially or fullycrosslinked resin networks which will no longer be thermoplastic innature and which are expected to exhibit enhancements, overcorresponding linear resins, in physical properties and/or in theirresistance to abusive conditions, such as exposure to organic solventsand elevated temperatures. A wide variety of means have been employed toproduce crosslinking in polycarbonate resin. These generally involve theincorporation of a suitably reactive chemical group either into theresin chain at its time of manufacture or as an additive to the resinafter manufacture, or both. These reactive groups and the reactions theyundergo are generally dissimilar from those characteristic ofpolycarbonate resin itself and are therefore prone to have detrimentalside effects on the physical and/or chemical properties of the polymer.The conventional test used to judge the success of these means forcrosslinking is to observe the formation of gels due to the crosslinkedmaterial when a resin sample is mixed with a solvent, such as methylenechloride, in which normal linear polycarbonate resin is highly soluble.

A new method has been discovered to prepare branched or crosslinkedpolycarbonate resin. This approach involves incorporating amultifunctional comonomer of better than two reactive groups into cyclicbisphenol carbonate oligomers. The thus prepared cyclic oligomers arethen reacted at elevated temperature with catalysis to yield highmolecular weight polycarbonate resin. Generally the polymerizationoccurs under melt conditions. This reaction is thought to proceed by amulti-step ring opening addition mechanism. During this polymerizationthe functional groups of the multifunctional comonomer are available forbuilding branches and/or for crosslinking one polycarbonate chain toanother polycarbonate chain.

This new method to prepare branched or crosslinked polycarbonate resinis an improvement over previous methods in that the resin is initiallylow in molecular weight and thus has low viscosity and is easilyprocessed into its desired forms. It is then converted under convenientreaction conditions to high viscosity branched resin or to crosslinkedresin. This is accomplished by incorporating into the resinmultifunctional comonomers with chemical groups with similar structureand reactivity to the repeat units of the resin so that the possibilityof detrimental side effects on resin properties are minimized.

SUMMARY OF THE INVENTION

In accordance with the invention, there is a composition comprising astructure of the formula: ##STR3## wherein X is selected from the groupconsisting of alkylene of two to twelve carbon atoms, inclusive,alkylidene of one to twelve carbon atoms, inclusive, cycloalkylene offour to twelve carbon atoms, inclusive, cycloalkylidene of four totwelve carbon atoms, inclusive, ##STR4##

a is zero or 1;

n is an integer of one to about fifteen;

R is alkylene of two to eight carbon atoms, inclusive or alkylidene ofone to eight carbon atoms, inclusive.

R¹ and R² are the same or different and are alkyl of one to four carbonatoms, inclusive or halo;

b and c are the same or different and are an integer of zero to four;

R³ and R⁴ are the same or different and are alkyl of one to eight carbonatoms, inclusive, or phenyl;

d and e are an integer of 0, 1 or 2 with the proviso that the sum of dand e is at least one.

It should be noted that the preponderance of the cyclic oligomers willhave only one multifunctional comonomer in the enclosed chain. However,some cyclic oligomers will have more than one multifunctional comomonerin the enclosed chain.

In further accordance with the invention, there is a compositioncomprising cyclic oligomers of Formula I in admixture with cyclicoligomers of the Formula II: ##STR5## wherein p is an integer from oneto about fifteen (15) and X, R¹, R², a, b and c have the same scope asabove.

Examples of the preparation and polymerization of cyclic oligomers aredescribed in copending Ser. Nos. 704,122, filed Feb. 22, 1985 and723,672, filed Apr. 16, 1985 and references contained therein, all ofwhich are incorporated herein by reference.

A further aspect of the invention is a composition comprising a veryhigh molecular weight aromatic polycarbonate polymer having a branchingsite from the reaction residue of ##STR6## wherein R, R³, R⁴, d and eare defined with the same scope as in Formula I.

Comonomers of Formula III can be incorporated into linear polycarbonateresins using standard interfacial conditions and then reacted under melttransesterification conditions to provide branched or crosslinked resin.However it is more advantageous to incorporate comonomers III intocyclic oligomers and then to react those oligomers under melttransesterification conditions to provide the branched or crosslinkedresin. This is due to the ability with cyclic oligomers to increase theratio of multifunctional and bifunctional reactive sites tomonofunctional reactive sites in a more convenient manner than thatemployed with interfacial resins. Thus, crosslinking density and extentis more uniform and can be higher. These resins can be used in thepreparation of useful articles such as fibrous reinforced material(composites). Such articles can be easily prepared by mixing orimpregnating the fiber with the low viscosity cyclic oligomers of thisinvention followed by thermal conversion to crosslinked polymer. Theremainder of the polymer consists at least essentially of residues ofthe dihydric phenol ##STR7## where X, R¹, R², a, b and c are previouslydefined in Formula I.

DESCRIPTION OF THE INVENTION

The incorporation of the compound(s) of Formula III into a cyclicoligomeric structure is done under standard cyclics producing reactionconditions. The cyclic oligomers are mixtures generally having degreesof polymerization of from about 2 to about 15. Those compositions haverelatively low melting points as compared to single compounds such asthe corresponding cyclic trimer. The cyclic oligomer mixtures aregenerally liquid at temperatures above 300° C. and most often attemperatures above 225° C.

The mixtures useful in this invention contain very low proportions oflinear oligomers. In general, no more than about 10% by weight, and mostoften no more than about 5%, of such linear oligomers are present. Themixtures also contain low percentages (frequently less than 30% andpreferably no higher than about 20%) of polymers (linear or cyclic)having a degree of polymerization greater than about 30. Such polymersare frequently identified hereinafter as "high polymer". Theseproperties coupled with the relatively low melting points andviscosities of the cyclic oligomer mixtures, contribute to theirutility.

These mixtures can be prepared by a condensation reaction involvingbishaloformates of the dihydric phenols of Formulae III and IV offormula ##STR8## wherein O--Ar--O is the reaction residue of either ofthe Formula III or IV dihydric phenols which have been reacted withphosgene or the bromo analogue, halo is chloro or bromo and n is aninteger of one to about six. Usually no more than one of the O--Ar--Oresidues is derived from a Formula III dihydric phenol; however therecan be two or more.

The cyclic oligomer forming reaction typically takes place interfaciallywhen a solution of said bishaloformate in a substantially non-polarorganic liquid is contacted with a tertiary amine from a specific classand an aqueous alkali metal hydroxide solution.

In one method for preparing the cyclic oligomer mixture, at least onesuch bishaloformate is contacted with at least one oleophilic aliphaticor heterocyclic tertiary amine and an aqueous alkali metal hydroxidesolution having a concentration of about 0.1-10M, said contact beingeffected under conditions resulting in high dilution of bishaloformate,or the equivalent thereof, in a substantially non-polar organic liquidwhich forms a two-phase system with water; and subsequently, theresulting cyclic oligomer mixture is separated from at least a portionof the high polymer and insoluble material present.

The tertiary amines useful in the preparation of the cyclicpolycarbonate oligomers generally comprise those which are oleophilic(i.e., which are soluble in and highly active in organic media) and moreparticularly those which are useful for the formation of polycarbonates.Reference is made, for example, to the tertiary amines disclosed in theaforementioned U.S. Pat. Nos. 4,217,438 and in 4,368,315, the disclosureof which is also incorporated by reference herein. They includealiphatic amines such as triethylamine, tri-n-propylamine, diethyl-n-propylamine and tri-n-butylamine and highly nucleophilic heterocyclicamines such as 4-dimethylaminopyridine (which, for the purposes of thisinvention, contains only one active amine group). The preferred aminesare those which dissolve preferentially in the organic phase of thereaction system; that is, for which the organicaqueous partitioncoefficient is greater than 1. This is true because intimate contactbetween the amine and bischloroformate is essential for the formation ofthe cyclic oligomer mixture. For the most part, such amines contain atleast about 6 and preferably about 6-14 carbon atoms.

The most useful amines are trialkylamines containing no branching on thecarbon atoms in the 1- and 2-positions. Especially preferred aretri-n-alkylamines in which the alkyl groups contain up to about 4 carbonatoms. Triethylamine is most preferred by reason of its particularavailability, low cost, and effectiveness in the preparation of productscontaining low percentages of linear oligomers and high polymers.

The aqueous alkali metal hydroxide solution is most often lithium,sodium or potassium hydroxide, with sodium hydroxide being preferredbecause of its availability and relatively low cost. The concentrationof said solution is about 0.2-10M and preferably no higher than about3-5M.

The fourth component in the cyclic oligomer preparation method is asubstantially non-polar organic liquid which forms a two-phase systemwith water. The identity of the liquid is not critical, provided itpossesses the stated properties. Illustrative liquids are aromatichydrocarbons such as toluene and xylene; substituted aromatichydrocarbons such as chlorobenzene, o-dichlorobenzene and nitrobenzene;chlorinated aliphatic hydrocarbons such as chloroform and methylenechloride; and mixtures of the foregoing with ethers such astetrahydrofuran.

To prepare the cyclic oligomer mixture according to the above-descrbedmethod, the reagents and components are maintained in contact underconditions wherein the bischloroformate is present in high dilution, orequivalent conditions. Actual high dilution conditions, requiring alarge proportion of organic liquid, may be employed but are usually notpreferred for cost and convenience reasons. Instead, simulated highdilution conditions known to those skilled in the art may be employed.For example, in one embodiment of the method the bischloroformate or amixture thereof with the amine is added gradually to a mixture of theother materials. It is within the scope of this embodiment toincorporate the amine in the mixture to which the bischloroformate isadded, or to add it gradually, either in admixture with the amine orseparately. Continuous or incremental addition of the amine isfrequently preferred, whereupon the cyclic oligomer mixture is obtainedin relatively pure form and in high yield.

Although addition of the bischloroformate neat (i.e., without solvents)is within the scope of this embodiment, it is frequently inconvenientbecause many bischloroformates are solids. Therefore, it is preferablyadded as a solution in a portion of the organic liquid. The proportionof organic liquid used for this purpose is not critical; about 20-80% byweight, and especially about 40-60%, is prepared.

The reaction temperature is generally in the range of about 0°-50° C. Itis most often about 0°-40° C. and preferably 20°-40° C.

For maximization of the yield and purity of cyclic oligomers as opposedto high polymer and insoluble and/or interactable by-products, it ispreferred to use not more than about 0.7 mole of bischloroformate perliter of organic liquid present in the reaction system, including anyliquid used to dissolve said bischloroformate. Preferably, about0.003-0.6 mole of bischloroformate is used. It should be noted that thisis not a molar concentration in the organic liquid when thebischloroformate is added gradually, since it is consumed as it is addedto the reaction system.

The molar proportions of the reagents constitute another importantfeature for yield and purity maximization. The preferred molar ratio ofamine to bischloroformate is about 0.1-1.0:1 and most often about0.2-0.6:1. The preferred molar ratio of alkali metal hydroxide tobischloroformate is about 1.5-3:1 and most often about 2-3:1.

Step II of the cyclic oligomer preparation method is the separation ofthe oligomer mixture from at least a portion of the high polymer andinsoluble material present. When other reagents are added to the alkalimetal hydroxide and the preferred conditions and material proportionsare otherwise employed, the cyclic oligomer mixture (obtained as asolution in the organic liquid) typically contains less than 30% byweight and frequently less than about 20% of high polymer and insolublematerial. When all of the preferred conditions are employed, the productmay contain 10% or even less of such material. Depending on the intendeduse of the cyclic oligomer mixture, the separation step may then beunnecessary.

Therefore, a highly preferred method for preparing the cyclic oligomermixture comprises the single step of conducting the reaction using asthe amine at least one aliphatic or heterocyclic tertiary amine which,under the reaction conditions, dissolves preferentially in the organicphase of the reaction system, and gradually adding bischloroformate,amine and alkali metal hydroxide simultaneously to a substantiallynon-polar organic liquid or a mixture of said liquid with water, saidliquid or mixture being maintained at a temperature in the range ofabout 0°-50° C.; the amount of bischloroformate used being up to about0.7 mole for each liter of said organic liquid present in the reactionsystem, and the molar proportions of amine and alkali metal hydroxide tobischloroformate being 0.2-1.0:1 and 2-3:1, respectively althoughgreater quantities of amine or alkali hydroxide can be employed ifdesired; and recovering the cyclic oligomers thus formed.

As in the embodiment previously described, another portion of saidliquid may serve as a solvent for the bischloroformate. Addition of eachreagent is preferably continuous, but may be incremental for any or allof said reagents.

In preparation of oligomers some of the carbonate linkages can bereplaced with ester linkages by use of ester containing bisphenolprecursors such as the reaction product of greater than one mole of abisphenol with one mole of a diacid chloride, such as terephthaloylchloride and/or isophthaloyl chloride, in the formulation of the cyclicoligomers. In this manner aromatic copolyester carbonate oligomers canbe prepared wherein up to all but one of the carbonate units has beenreplaced by an aromatic carboxylic ester unit.

When a separation step is necessary, the unwanted impurities may beremoved in the necessary amounts by conventional operations such ascombining the solution with a non-solvent for said impurities.Illustrative non-solvents include ketones such as acetone and methylisobutyl ketone and esters such as methyl acetate and ethyl acetate.Acetone is a particularly preferred non-solvent. Recovery of the cyclicoligomers normally means merely separating the same from diluent (byknown methods such as vacuum evaporation) and, optionally, from highpolymer and other impurities.

With respect to the structure of the formulae, X is preferably alkyleneof two to six carbon atoms, inclusive, alkylidene of one to six carbonatoms, inclusive, cyclalkylidene of six to twelve carbon atoms,inclusive ##STR9##

a is preferably 1.

R is preferably alkylene of two to four carbon atoms, inclusive oralkylidene of one to four carbon atoms, inclusive.

R¹ and R² are the same or different and are preferably alkyl of one tothree carbon atoms, inclusive, chloro or bromo.

b and c are the same or different and are preferably 0, 1 or 2.

d and e are preferably 1.

R₃ and R₄ are the same or different and those alkyl without a βhydrogen, e.g. methyl, phenyl, benzyl 2,2-dimethylpropyl are preferred.Most preferable are methyl and phenyl.

The cyclic oligomers are converted to linear polymers by standard meltreaction conditions utilizing transesterification type catalysts.Generally transesterifications are carried out in the melt state ingeneral accordance with known processes described, inter alia, in TheEncyclopedia of Polymer Science, Vols. 9 and 10 (1969); Chemistry andPhysics of Polycarbonates, H. Schnell, Vol. 9, John Wiley and Sons, Inc.(1964); Polycarbonates, Christopher and Fox, Reinhold Corporation,(1962); U.S. Pat. Nos. 4,217,438; 4,329,443 and 4,217,438, all of whichare hereby incorporated by reference.

The transesterification catalysts used in the preparation of the instantpolycarbonate resins are any of the well known and conventionaltransesterification catalysts. These-catalysts include the organic andinorganic bases, the organic and inorganic protic acids, and the Lewisacids. Some illustrative nonlimiting examples of organic and inorganicbase catalysts include sodium metal, lithium hydroxide, sodiumcarbonate, sodium acetate, sodium methylate, sodium borohydride,isopropylamine, pyridine, sodium benzoate, sodium phenoxide, sodiumaluminumhydride, and sodium boronhydride. Some illustrative non-limitingexamples of protic acid catalysts include hydrochloric acid,hydrofluoric acid, hydrobromic acid, sulfuric acid, sulfonic acid,methanesulfonic acid, benzene sulfonic acid, and phosphonic acid. Someillustrative non limiting examples of Lewis acid catalysts includeborontrifluoride, stannic chloride, and dialkyl tin oxide. Other Lewisacid catalysts are disclosed, inter alia, in U.S. Pat. Nos. 4,045,464,3,255,236, and 4,182, 726, all of which are incorporated herein byreference. Other protic acid catalysts are disclosed, inter alia, inU.S. Pat. No. 3,767,648, which is incorporated herein by reference.

The amount of the catalyst employed is a catalytic amount. By catalyticamount is meant an amount effective to catalyze the reaction. Generally,molar ratios of catalyst to dihydric phenol in the range of from about1×10⁻⁵ to 1 to about 1×10⁻¹ to 1 can be used.

The crosslinking which occurs in the polycarbonates is generallyphysically manifested by the appearance of gels when the polycarbonateresin is placed in an organic solvent such as methylene chloride. Thenoncrosslinked polycarbonate will go into solution; the crosslinkedpolycarbonate will remain in gel form.

The crosslinked residue and useful articles made from this invention mayoptionally contain the commonly known and used additives such as, forexample, antioxidants, mineral fillers, reinforcing agents, impactmodifiers, colorants, ultraviolet radiation absorbers such as thebenzophenones, benzotriazoles, and cyanoacrylates; color stabilizerssuch as the organophosphites described in U.S. Pat. Nos. 3,305,520 and4,118,370, both of which are incorporated herein by reference;hydrolytic stabilizers such as the epoxides described in U.S. Pat. Nos.3,489,716; 4,138,716 and 3,839,247, all of which are incorporated hereinby reference, and flame retardants.

Some particularly useful reinforcing agents which may be used separatelyor in combination are carbon, aramid, glass and boron fibers and otherreinforcements which may be chopped, woven, knit, braided, wound orshaped by any conventional method.

Some particularly useful flame retardants are the alkali and alkalineearth metal salts of organic sulfonic acids. These types of flameretardants are disclosed, inter alia, in U.S. Pat. Nos. 3,933,734;3,938,851; 3,926,908, 3,919,167; 3,909,940; 3,853,396; 3,931,100;3,978,024; 3,953,399; 3,917,599; 3,951,910 and 3,940,366, all of whichare incorporated herein by reference.

The following are examples. These examples are intended to illustratethe embodiments within the inventive concept. The examples are not meantto narrow the inventive concept.

EXAMPLE 1 PREPARATION OF A 2 MOLE % CYCLIC OLIGOMER COPOLYMER UTILIZINGBIS(4-HYDROXY-3-METHOXYCARBONYLPHENYL) METHANE WITH BISPHENOL-A.

a. Preparation of bischloroformate oligomers. A 1000 ml. four neck flaskwas fitted with a mechanical stirrer, a pH probe, an aqueous causticinlet tube and a Claisen adapter to which was attached a dry icecondenser and a gas inlet tube. To the flask was added 200 ml ofmethylene chloride, 200 ml. water, 1.26 g (0.004 mole) bis(4-hydroxy-3-methoxycarbonyl phenyl) methane and 44.7 g (0.196 mole)bisphenol-A. To the flask was then added phosgene at 2.0 g/min for 21min. (42 g, 0.42 mole) with the pH maintained in the range 2 to 5 byaddition of 25 wt. % aqueous sodium hydroxide. After completion ofphosgene addition, the reaction mixture was stirred for an additional 15min, and the methylene chloride layer was removed. The methylenechloride solution was used directly in the cyclization reaction.

b. Cyclization of the bischloroformate oligomers. A 1000 ml. flask wasfitted with a mechanical stirrer and an addition funnel containing thebischloroformate oligomer solution prepared above. To the flask wasadded 80 g of 50% aqueous sodium hydroxide, 120 ml. water, 300 ml.methylene chloride and 6.4 ml. (0.046 mole) triethylamine. Thebischloroformate oligomer solution was then added drop-wise over onehour to the slowly stirred reaction mixture. The reaction mixture wasstirred an additional 15 minutes and then quenched with 3N aqueous HCLto pH of 3. The methylene chloride layer was removed, washed with 200 mlof 0.01M aqueous HCl, then washed with 200 ml of distilled water, driedover MgSO₄, filtered and the solvent removed under vacuum to yield 42 gof a white solid. To that solid was then added 500 ml acetone. Theresultant slurry was stirred for 30 minutes, then filtered and thesolvent removed under vacuum to yield 24 g of the acetonesoluble cyclicoligomers, which were then used directly in the polymerization reaction.

c. Polymerization of the cyclic oligomers. To 6 g (2.3×10⁻² mole) of thecyclic oligomers from above dissolved in 25 ml methylene chloride wasadded 0.009 g (2.3×10⁻⁵ mole) tetramethylammonium tetraphenyl boratedispensed in 5 ml. methylene chloride. The solvent was then removedunder vacuum and the resultant residue dried for 4 hours at 120° C. A 5g sample of the mixture was then compression molded at 250° C. for 20minutes into a 1.5 inch diameter disk.

A 2.0 g sample from the disk was then swelled in 40 ml methylenechloride and the resultant gel repeatedly soaked and washed withmethylene chloride until no additional soluble resin was observed to beremoved from the gel. The gel was then dried and weighed (0.81 g, 41%gel). The intrinsic viscosity of the soluble portion (methylenechloride, 25° C.) was 1.97 dl/g.

EXAMPLE 2 PREPARATION AND POLYMERIZATION OF A 4 MOLE % CYCLIC OLIGOMERSCOPOLYMER OF BIS (4-HYDROXY-3-METHOXYCARBONYLPHENYL)METHANE WITHBISPHENOL-A

The same procedures as described above in Example 1 were used, startingwith 2.53 g (0.008 mole) of bis (4-hydroxy-3-methoxycarbonylphenyl)methane and 43.8 g (0.192 mole) bisphenol-A.

The resultant resin exhibited 65% gels and an intrinsic viscosity of thesoluble portion of 0.940 dl/g.

PREPARATION OF CONTROL SAMPLE

A sample prepared essentially by the same procedure as above usingbisphenol-A and no bis(4-hydroxy-3-methoxycarbonyl phenyl) methaneexhibited 0.4% gels and intrinsic viscosity of 1.04 dl/g.

As is observed from the data, the incorporation of a branching agentwithin the cyclic oligomers brings about a cross-linked polycarbonate atthe levels used as opposed to the standard linear polycarbonate. Theamount of branching agent, that is the compound of Formula III, can varywidely and still obtain a nonlinear system. At the lower percentbranching agent, branched rather than cross-linked polycarbonates canoccur. At the upper end of the range essentially all the incorporatedagent produces cross-linked resin. The percentage of branching agentbased on diphenol+branching agent is generally from about 0.1 to 10 molepercent and more specifically from about 0.5 to 5 mole percent of thediphenol plus branching agent.

What is claimed is:
 1. A composite material comprising a fibrous ormatted material to which has been added or impregnated a liquid cyclicoligomer of the formula: ##STR10## wherein X is selected from the groupconsisting of alkylene of two to twelve carbon atoms, inclusive,alkylidene of one to twelve carbon atoms, inclusive, cycloalkylene offour to twelve carbon atoms, inclusive, cycloalkylidene of four totwelve carbon atoms, ##STR11## a is zero or 1; n is an inter of one toabout fifteen;R is alkylene of two to eight carbon atoms, inclusive, oralkyhlidene of one to eight carbon atoms, inclusive; R¹ and R² are thesame or different and are alkyl or one to four carbon atoms, inclusiveor halo; b and c are the same or different and are an integer of zero tofour; and R³ and R⁴ are the same or different and are alkyl of one toeight carbon atoms, inclusive, or phenyl; and d and e are individuallyintegers of 0, 1 or 2 with the provisio that d+e is at least one; andthe cyclic oligomer polymerized in situ to a high molecular weightaromatic polycarbonate.